1. Field of the Invention
The present invention relates to equipment for implanting oxygen ions into a wafer, and more particularly to oxygen ion implantation equipment that can improve the uniformity of the thickness of an SOI (silicon on insulator) layer of a SIMOX (Separation by IMplanted OXygen) wafer.
2. Description of the Related Art
Conventionally, in oxygen ion implantation equipment of this type, a wafer is heated by a lamp heater, and, as the lamp heater, 10 to 15 halogen lamps arranged at regular intervals are used to heat the whole surface of the wafer uniformly. The lamp heater is used at the time of oxygen ion implantation in the production process of a SIMOX wafer, and, at present, the commercially available SIMOX wafer is produced by a method called an MLD (modified low dose) method. In the MLD method, oxygen ion implantation is performed in two stages (for example, refer to Patent Document 1). First oxygen ion implantation is performed by heating a silicon wafer to 200 to 700° C., preferably to about 550 to 575° C., and then second oxygen ion implantation is performed by heating the silicon wafer to −269 to 300° C., preferably to about 25 to 200° C. The first oxygen ion implantation helps maintain the single-crystal surface of the silicon wafer by heating the silicon wafer, and forms a layer containing a high concentration of oxygen. In the second oxygen ion implantation, an amorphous layer is formed. Then, high-temperature heat treatment is performed with an oxygen/argon gas mixture, whereby an SOI structure is formed.
Patent Document 1    U.S. Pat. No. 5,930,643 (claims 1, 6, 7, 14, and 15)